Power unit



Juhe 1, 1954 MQL 2,680,017

POWER UNIT Filed Dec. 15. 1950 2 Sheets-Sheet 1 I00 I28 :07 I38 124 57 us HO I36 I30 -34 us I32 98 INVENTORI, 94 B8 gnaw RT ammsoo.

S. B. M LEOD June 1, 1954 POWER UNIT 2 Sheets-Sheet 2 Filed Dec. 15 1950 INVENTOR.

STEW RT B. MCLEOD BY *0 ATTOR EYS Patented June 1, 1954 POWER UNIT Stewart B. McLeod, Dearborn, Mich., assignor to Detroit Harvester Company, Detroit, Mich., a corporation of Michigan Application December 15, 1950, Serial No. 200,952

. 16 Claims.

1 The present invention relates to a power unit and more particularly, to a combination electric motor, hydraulic pump, and hydraulic device combined into a compact self-contained unit.

It is an object of the present invention to provide a power unit of the character described, particularly adapted to serve as an actuator for raising and lowering windows in a vehicle.

' It is a further object of the present invention to provide a self-contained electric-hydraulic power unit designed to be self-locking in one :direction so as to prevent opening of the window by the application of mechanical force when the pump is not operating,,while permitting manual reverse movement.

It is a further object of the present invention to provide an electric-hydraulic power unit including a pump, a piston and cylinder device arranged to have differential fluid inflow and outflow during operation, a fluid reservoir adapted to receive excess flow of fluid or to furnish fluid as required in the operation of the device, check valves controlling flow of fluid into said reservoir, 2. by-pass around the motor, and means effective to close both check valves upon the application of mechanical force to the power device in a direction tending to cause more out- Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a fragmentary phantom perspective showing the application of the improved power unit to window lifters.

Figure 2 is a side elevation partly in section of the improved power unit.

Figure 3 is a top plan view of the power unit shown in Figure 2.

Figure 4 is a bottom plan View of the power um Figure 5 is a section on the line 5--5, Figure 3.

Figure 6 is a flow diagram of the system.

Referring now to the drawings, in Figure 1 there is illustrated a portion of an automobile 10 having a door I2 and a body structure It. In the door 12 there is provided a window 56 adapted to be raisedand lowered vertically. Rearwardly of the vehicle there is a window section it including a frame 20 which is pivoted as indicated at 22 for rocking movement to open and close the window section l8.

The window i6 is provided with suitable guide means for controlling its vertical movement and is operatively connected to the power unit indi-;

cated generally at 24, by a lever 26' connected to the piston rod 28 of the power unit, the lever 26 being pivoted at one end to a bracket 30 and having a pin 32 at its other end slidable longitudinally in the slot 3 t of bracket 36 carried by the window frame. The power unit 24 is pivotally supported by a bracket 3! suitably secured within the door cavity. The rear window section it is moved by a similar power unit 24, the piston rod 28 of the power unit being connected to a lever 38 pivoted to the body of the vehicle as indicated at 46 and having a pin 42 at its other end slidable in a slot 44 provided in the bracket 46 carried by the window. In this case the power unit 24 is pivotally supported on a bracket 41 mounted within the frame of the vehicle below the rear window Hi.

In power units controlling the movement of windows of this type it is highly desirable to provide automatically operable locking means which prevent the windows being mechanically opened while the power unit is de-energized. At the same time, it is desirable to include means insuring that dangerous forces will not be applied to the windows in the event that an occupant of the vehicle interposes a hand or other part of his body between the window and the door or body frame. These two requirements are taken care of by the present construction as will subsequently be described.

Referring now to Figures 2-5, the power unit 24 comprises a unitary base 50 in the form of a casting. The base 50 is somewhat elongated and at one end is provided with a recessed cylindrical seat 52 for the reception of an electric motor 54. At the opposite side of the base 5% and at the same end as the motor 54, there is provided a cylindrical. recess 56 adapted to receive a pump El consisting of an internal gear 58 and an external gear 66. In practice, the internal gear is provided with one more teeth than are provided on the external gear or pinion 66. The pump housing which is formed in part by the cylindrical recess 56 is closed at the lower side by a removable plate 6| secured in place by clamping screw 62. Gear elements 58 and 60 are rotated by the motor and for this purpose the motor shaft 63 extends through an opening provided through the base 50 from the motor seat 52 to the recess 56.

At the opposite end of the base 56 there is provided a. cylinder seat 64 surrounded by an annular seating flange 66. The cylinder seatfltt and flange 66 together serve as a closure for the otherwise open end of the power cylinder 68 and also serve to mount the cylinder in operative position. Outwardly of the annular flange 66 is a cylindrical groove W in which is received a ring I2 bolted or otherwise secured in place as by the bolts i i. As indicated in Figure 2, the lower end of the cylinder 58 includes an outwardly extending radial flange I6 engaged beneath the clamping ring '52 and of course, suitable sealing means are provided.

At the same end of the base 55 and at the side thereof opposite to the cylinder 58, there is provided. a pivot support It having a transverse opening 8! therethrough and strengthened by supporting webs 32. It will be observed that the axis of the opening 89 is perpendicular to and intersects the axis of the cylinder 68, so that the power unit as an assembly will in use rock about an axis intersecting the axis of the cylinder. Located within the cylinder 58 is a piston 32 provided with a piston rod 28 which extends through the cylinder head 83 at the upper end of the cylinder.

Formed within the body of the base 58 and in communication with the bottom of the recess 55 are a pair of ports 99 and 92 in communication with opposite sides of the pump. The pump is designed to be run in opposite direction resulting in a reverse flow of fluid therethrough and for this purpose the motor is also reversible. In communication with the port 98 and within the body of the base 59 is a flow passage 55d which is closed at its outer end by a plug 95. Communicating with the passage 53 2 is another passage 98 which as best seen in Figure extends through the cylinder seat I34 and thus afiords communication between the lower end of the cylinder 68 and the pump port 98. A second longitudinally extending passage Elli is provided within the body of the base 50 and extends to one end thereof where it receives a fitting N22. The head 88 of the cylinder I58 carries a second fitting I94 and the fittings are interconnected by a metal tube or conduit I06, thus affording communication between the upper end of the cylinder and the valve port 92.

Inasmuch as the power unit operates to raise and lower the windows of a vehicle, it is essential to insure that sufiicient force is not exerted on the window to cause injury to an occupant who catches his hand or other part of his body between the window and the frame of the door or vehicle. It is also desirable to permit the motor to run after full stroke or the piston. In the present case this is taken care of by providing a small amount of clearance indicated at i5? in Figure 2, and indicated diagrammatically in Figure 6, between one or both of the gear elements 58, 60 and the closure plate 6i. Thus, if the motor continues to run when the piston rod 8% is mechanically held against movement, there will be a circulation of fluid within the pump between the ports 90 and 92. This flow is insuflicient to seriously decrease the elliciency of the pump in normal operation, but is suflicient to limit the force with which the piston rod 23 is urged upwardly.

Obviously, instead of relying upon a constant amount of clearance between opposite end walls of the pump chamber and the rotating pump elements, a movable end plate could be provided in contact with one side of the pump elements but provided with yieldable means so that upon attainment of sufficient pressure at the discharge side of the pump the plate could yield to permit a by-pass flow within the pump.

Inasmuch as the piston rod 28 occupies the portion of the cylinder 68 above the piston 84, whereas no similar element is present in the portion of the cylinder beneath the piston, it will be apparent that a difierential flow of hydraulic fluid to and from the cylinder 68 takes place upon movement of the piston 85. Thus, when the piston is moved upwardly by a flow of hydraulic fluid under pressure into the lower end of the cylinder, more fluid will flow into the lower end of the cylinder than is displaced from the upper end of the cylinder by movement of the piston therein. Conversely, as the piston moves downwardly there is a greater flow of hydraulic fluid out of the lower end of the cylinder than inflow of fluid into the upper end of the cylinder.

This difierential flow requires a reservoir to accommodate the excess flow out of the cylinder upon movement of the piston in one direction and to supply the excess fluid required to move the cylinder in the opposite direction. In the present case the reservoir is provided in the form of a cavity H0 within the base 50. As best seen in Figure 3, where the outline of the cavity H0 appears in dotted lines, it will be observed that the reservoir is of a minimum width on the center line connecting the axis of the motor and the axis of the cylinder. At this point the width of the reservoir is determined by the space between the screw receiving bosses III which are also seen in Figure 5. At either side of this center line it is enlarged longitudinally of the base 50. The width of the reservoir on the adjacent center line appears directly in Figure 2 of the drawing. The reservoir no is completed by a removable cover plate H2 provided with one or more removable filling plugs H4.

As best seen in Figure 5, the hydraulic fluid flow passages 94 and IQS are interconnected by a transverse passage H6 which terminates at its outer ends in two enlarged Valve chambers IIB and I20, the juncture between the transverse passage HE and the chambers H8 and I20 constituting valve seats 22 and I24 respectively. It will be observed that flow passages 9 and H30 connect directly with the enlarged valve chainbers H3 and I29. Outer ends of the valve chambers I l8 and I253 are closed by removable plugs I26 and 528 respectively. A passage I38 connects an intermediate portion of the transverse passage I E6 with the reservoir H0.

Located within valve chambers I I8 and I29 are ball valves I32 and I35 respectively, and intermediate the ball valves is a compression spring I36. The plugs IE5 and I23 each include inwardly extending portions I38 adapted to limit outward movement of the adjacent ball valve away from its seat. To accomplish the results desired in a window lift unit, plug I26 is arranged to permit valve I32 to move a relatively great distance from its seat, while valve I34 is closely spaced from its seat.

The operation of the hydraulic system as previously described, depends in part upon the selection of the spring I 35 so as to control the flow of fluid in a predetermined manner.

With the parts in the position illustrated in Figures 2 and 6, which corresponds to a lowered or open position of the window, if it is desired to raise the window the motor 55 is energized in the proper direction thus rotating the pump Construction the entire hydraulic system exclusive of the reservoir remains completely filled with hydraulic fluid at all times so that response is instantaneous in either direction. Accordingly, as the piston 84 moves upwardly fluid is expelled from the upper end of the cylinder but in a quantity less than the inflow of fluid into the bottom of the cylinder. Hydraulic fluid flows out through the fitting I04, the conduit I06, the fitting I02, and the flow passage I00, back to the pump port 92 and to the inlet side of the pump. However, since more fluid is required to move the piston upwardly than is returned through the return line, excess hydraulic fluid is required to be supplied from the reservoir I I0. This fluid is supplied through the passage I30, the transverse passage IIB and past the ball valve I34 into the suction flow line I00, and thence to the pump. Operation of the pump establishes a relatively high pressure in the passage 04 and this pressure, acting on the ball valve I32, closes this valve and prevents fluid being forced into the reservoir from the pressure side of the system.

'If the piston 84 is in upper position and it is desired to lower the same by power, the direction of rotation of the motor 54 and the pump is reversed, with the result that the passage I00 becomes the pressure flow passage and fluid flows from this passage through the fitting I02, conduit I06, fitting I04 into the upper end of the cylinder. Pressure in the passage I00, and hence in the valve chamber I20, closes the valve I34 and prevents fluid from the pressure side of the system being forced into the reservoir IIO. Downward movement of the piston 84 expels hydraulic fluid through the passages 98 and 94 to the pump inlet port 90. However, since more fluid is expelled from the pump than is being delivered to the pump, there is an excess of fluid in the return or suction side of the system. Since the valve I32 is widely separated from its seat, and since pressure in suction line 94 is much less than in the pressure side of the system, valve I32 remains open, and flow of this excess fluid past the valve I32 is permitted. For this purpose the effectiveness of the spring I36 is such that in conjunction with the spacing of the valve from its seat, the spring holds the valve I32 off its seat when the pump is running in a direction such that the passage 94 is at the suction or inlet side of the pump while permitting it to close under manual operation, as will subsequently be described. Thus, the excess fluid expelled from the cylinder 68 is caused to flow into the reservoir I I0 during downward movement of the piston 04.

If the motor is stopped with the piston 84 in its uppermost position corresponding to closed position ofthe windows, the hydraulic system operates to provide an effective lock which will prevent unauthorized entry into. the vehicle by forcing the window downwardly. With the piston 84 at the top or upper position of the cylinder 68 and with the pump inoperative, if a force is applied to the window tending to move the piston 04 downwardly, the first effect is to cause a flow of fluid through the passages 98 and 04 to the pump port 90. Since the pump is idle, flow therethrough is restricted and pressure builds up instantly in passage 94 and chamber I I8.

The pressure built up in passage 94 and valve chamber I I8 is inherently greater than the pres,- sure at this side of the system when the piston is moving down under power operation, with the several factors.

pump operating. This is due to a combination of When the pump is operating in a direction to cause the piston to move downwardly, work is being done and power consumed to accomplish this movement, 50 that the pressure built up below the piston has to be very substantially less than the pressure above the piston doing the work. Moreover, the effective areas at opposite sides of the piston operate to increase the pressure differential. In addition, the inlet side of the pump is tending to create a suction in line 94. All of these factors combine to insure that under power operation, flow into the reservoir past valve I 32 takes place under relatively low pressure. However, when forces are applied to the window with the pump not operating, the leverage of the window operating system provides a large mechanical advantage. Moreover, the window movement is initially opposed by static friction, and when this is overcome, it moves suddenly and creates a surge of pressure below the piston. This results in closure of valve I32. Flow through the by-pass in the pump causes valve I34, with its relatively small clearance, to close at once, and a solid hydraulic block is established.

On the other hand, when the pump is not operating, the windows may be raised manually without difficulty, and will remain locked by the hydraulic block in upper position. In this case, upward movement of the piston will close valve 134, but the by-pass flow through the pump will not close valve I32 to create the hydraulic block. This is for the reason that the excess flow required to fill the cylinder beneath the piston creates negative pressure in line 94, thus opening valve I32 and permitting fluid to flow out of the reservoir IIO into line 94.

The foregoing operation depends in part upon the effectiveness of the spring I36 but is also affected by the location of the inner end of the projecting portions 138 of the plugs I26 and I28. Accordingly, operation of the system is variable by adjustment of the plugs I26 and I23.

Briefly reviewed, when the pump is operating the ball valve at the pressure side of the pump is closed and the ball valve at the suction side of the pump remains open, whether the flow past the ball valve is into or out of the reservoir. However, when the pump is idle, mechanical forces tending to move the piston 84 downwardly result in the development of forces which close both of the ball valves. Since the entire hydraulic system is completely filled at all times, closure of both of the ball valves blocks further movement of the piston. On the other hand, mechanical forces applied upwardly to the piston are effective to raise the piston. This results in closure of the valve 134 but the by-pass flow of fluid through the pump permits the piston to move upwardly. The excess fluid required to fill the cylinder below the piston produces a negative pressure in passage 94 and the fluid flows out of the reservoir IIO into the passage 94.

The drawings and the foregoing specification constitute a description of the improved power unit in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is;

1. In a motor vehicle, in combination, a frame part having opposed walls defining a restricted space, an opening through said walls, a window movable from a closed position within said opening to an open position within said space, a power unit within said space for raising and lowering said window, said power unit comprising a unitary base, an electric motor on said base, a pump recess in said base, a pump in said recess, drive means connecting said pump and motor, a piston and cylinder device on said base, passages at least partly located in said base connecting said pump and cylinder, and window operating means connecting the piston of said device to said window.

2. The combination defined in claim 1 in which said base includes an enlarged cavity therein constituting a fluid reservoir, and passages in said base connecting said reservoir and said pump.

3. Power mechanism for raising and lowering windows and for preventing opening of the windows the application of force directly to the window which comprises a cylinder, a piston in said cylinder, a piston rod connected to said piston and extending outwardly from one end thereof, said piston rod having means on its outer end for connection to window operating mechanism in such relation that movement of the rod out of the cylinder results in closing of the window, a reversible hydraulic pump, means for providing a restricted flow of fluid between opposite sides of said pump when said pump is idle, flow passages connecting opposite sides of said pump to opposite ends of said cylinder, a reservoir, feed passages connecting said reservoir to said flow passages, check valves in said feed passages, resilient means normally biasing both of said valves to open position and constructed and arranged to permit simultaneous closure of both of said valves in response to a pressure in said flow passages developed by the application of an opening force to the window with the pump stopped, but to remain open in the suction flow passage when said pump is running.

4. Mechanism as defined in claim 3 in which portions of said feed passages are aligned, said valve seats face outwardly of the aligned portions, and the resilient means comprises a single compression spring engaging at its opposite ends the inner portions of said valves.

5. Mechani m as defined in claim 4 in which the check valve in the side of the system connected to the end of the cylinder remote from the piston rod is arranged to close only under higher pressure than said other check valve.

6. A seli'locking power unit comprising a reversible pump, a cylinder, a piston in said cylinder, a piston rod on said piston, fluid flow passages connecting opposite sides of said pump to opposite ends of said cylinder, means providing for a restricted flow of fluid between opposite sides of said pump, a fluid reservoir, feed passages connecting said reservoir to each of said flow passages, check valves in said feed passages resilient means normally holding both of said check valves open but providing for simultaneous closure thereof, said valves including means constructed and arranged to provide for closure of said valves at diiierent pressures.

'7. A unit as defined in claim 6 in which the resilient means and valves are constructed and arranged to permit closure of the check valve at the pressure side of the pump and to keep the valve open at the suction side thereof when the pump is operating, and to permit closure of both valves when fluid is displaced from the cylinder at the side opposite to the piston rod by the application of forces directly between said piston and cylinder when the pump is idle.

8. A unit as defined in claim 7 in which portions of said feed passages are in alignment and direct communication with each other, valve seats are provided at opposite ends of said aligned portions, said check valves are disposed outwardly of said seats, said feed passages include a common branch intermediate said seats and connected to said reservoir and said resilient means comprises a compression spring interposed directly between said valves and located in said aligned portions of the feed passages.

9. A power unit for raising and lowering vehicle windows comprising a unitary base, a recess in said base, a pump in said recess, a cylinder support on said base, a power cylinder having one end supported and closed by said support, a first flow passage in said base connecting one side of said pump with the supported end of said cylinder, 21. second flow passage connecting the other side of said pump with the other end of said piston, a portion of said second flow passage being located within. said base, a cavity with. in said base forming a fluid reservoir therein, a connecting passage in said base extending transversely of said flow passages and terminating in enlarged valve chambers in communication with said flow passages, valve seats at the junction between the ends of said transverse passage and said chambers, valves in said chambers, a passage connecting said reservoir to said transverse passage intermediate said valve seats resilient means normally holding both of said valves ofi their seats but yieldable to permit closure of one or both of said valves upon establishment of a predetermined pressure in said valve chambers, means providing for a restricted flow of fluid between opposite sides of said pump, a piston in said cylinder, a rod connected to said piston, said resilient means being of such strength as to be yieldable under pump pressure to permit closure of the valve in the chamber connected to the pressure side of said pump but to maintain the other valve open when the pump is operating, and to be yleldable to permit closure of both of said valves when mechanical force is applied tending to move the piston in the cylinder in a direction away from the piston rod.

10. Structure as defined in claim 9 in which said resilient means is a compression spring interposed directly between said valves.

11. Structure as defined in claim 10 in which said valves are balls.

12. Structure as defined in claim 9 in which means providing for a restricted flow of fluid between opposite sides of said pump comprises means providing clearance between parts of said pump.

13. A self-locking power unit comprising a hydraulic device having a differential input and output flow, a reversible pump for supplying fluid to said device, passages connecting opposite sides of said pump to opposite sides of said device,

a fluid reservoir in communication with both of closure of both of said valves in response to fluid flow resulting from the application of mechanical forces to said hydraulic device in a direction causing greater output flow than input flow while said pump is idle.

14. Structure as defined in claim 13 in which the valve controlling flow from the passage connected to the side of the hydraulic device requiring the larger flow is provided with abutment means locating said valve in open position relatively widely separated from its seat as compared to the other valve.

15. In a power unit of the character described, a pair of passages connected between opposite sides of a reversible pump and opposite ends of a power cylinder including a piston and piston rod, a transverse passage terminating at each end in "an enlarged valve chamber, a reservoir in communication with said transverse passage intermediate its ends, a valve seat at the inner end of each chamber, each of said chambers being in communication with one of said pair of passages, a valve in each of said chambers, a plug closing the outer end of each chamber including an abutment portion engageable by the valve in said chamber to limit movement of said valve away from its seat, a compression spring in said transverse passage engaging both of said valves and permitting closure of both of said valves at different chamber pressures, the valve in the chamber communicating with the passage connecting said pump to the end of said cylinder remote from said piston rod being spaced further from its seat in open position than said other valve, and means independent of said aforementioned passages providing for a restricted flow of fluid between opposite sides of said pump.

16. A self-locking power unit comprising a hydraulic device having a diflerential input and out put flow, a reversible pump for supplying fluid to said device, passages connecting opposite sides of said pump to opposite sides of said device, a fluid reservoir in communication with both of said passages, check valves controlling flow of fluid into said reservoir from either of said passages, means providing for a restricted flow of fluid between opposite sides of said pump, and resilient means normally retaining both of said valves open, said valves including means constructed and arranged to provide for simultaneous closure thereof to block movement of said hydraulic device by the application of external mechanical force in one direction when said pump is idle, but permitting reverse movement of said hydraulic device by external force with said pump idle.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,078,127 Coleman Nov. 11, 1913 1,931,637 Wahl Oct. 24, 1933 2,020,618 Persons Nov. 12, 1935 2,061,530 Wile Nov. 21, 1936 2,132,325 Soldatti Oct. 4, 1938 2,259,264 Parsons Oct. 14, 1941 2,388,755 McLeod Nov. 13, 1945 2,405,061 Shaw July 30, 1946 2,425,391 Parsons Aug. 12, 1947 2,475,304 Barifil July 5, 1949 FOREIGN PATENTS Number Country Date 781 Great Britain 1898 

